Certain supercars, such as the Ferrari 458 Italia, provide an engine speed flare during startup. In particular, these vehicles have an engine speed profile that includes a very short duration rise to a relatively high peak flare speed followed by a short duration decrease to an engine idle speed. This combination can be referred to as an engine speed flare. Such a high peak flare speed and such a rapid rise and fall in the startup engine speed profile (i.e., engine speed flare), which simulates racecar-like response, is possible in these supercars, including in the Ferrari 458 Italia, due to the use of a lightweight reciprocating assembly and/or a high performance engine that provides a large compression ratio, particularly as compared to conventional vehicle engines. The use of a lightweight reciprocating assembly can include the provision of an engine arrangement suitably employing a single plane crankshaft. Unlike conventional multi-pin counterweighted crankshafts, the single plane crankshaft has a reduced mass and therefore can be increased to a desired engine speed much faster than a conventional engine.
With reference to FIG. 1A, an example supercar engine speed profile is shown. This engine speed profile, which can be the engine speed profile found on the Ferrari 458 Italia vehicle and used particularly at startup, has a small throttle blip that results in the illustrated supercar engine speed profile wherein the engine increases at startup to a peak flare speed (e.g., 2200 RPM) in a very short duration (e.g., 115 msec) and then rapidly decreases to an engine idle speed (e.g., 700 RPM) in slightly longer, but still very short, duration (e.g., 375 msec). As mentioned above, this desired engine speed profile of the supercar is possible due to the use of a lightweight reciprocating assembly (e.g., including a single plane crankshaft without counterweights) and/or a large compression ratio engine.
In contrast, with reference to FIG. 1B, an example standard vehicle engine speed profile is shown with a corresponding throttle profile shown immediately thereabove. This engine speed profile, which can be the engine speed profile for a conventional sedan-type vehicle, has the illustrated small throttle blip (e.g., opening the throttle to 2.7 degrees) resulting in the illustrated standard vehicle engine speed profile. As shown, the peak flare speed (e.g., 1,400 RPM) is reduced relative to supercar engine speed profile of FIG. 1A and the rise and fall duration of the flare (e.g., 1,000 msec for each of the rise and the fall) is very long and occurs for a much longer duration as compared to the supercar vehicle flare profile. This slower response can be caused by the relatively large rotational inertia associated with more conventional engines (e.g., due to the use of a multi-pin counterweight crankshaft).